I have completed the quest claim Narsis: Fools' Gold as my quest showcase. I've added everything as specified in the claim, with the addition of the pre-existing npc Barsille now being involved in the quest as the one hired to kill Urinius on Duthar'jo's behalf, and as the one whose room upstairs contains the note proving their guilt.

As outlined in the claim, there are four endings: the player gives Ursinius the evidence, the player gives Duthar'jo the evidence in exchange for directions to an unclaimed diamond mine, the player learns that Ursinius tried to kill Duthar'jo first and uses this information to blackmail Ursinius out of more money in exchange for the evidence, and the player gives the guards the evidence in exchange for nothing.

After each of these endings, Ursinius and Duthar'jo disappear, and after every ending except the one where the player gives the evidence to Duthar'jo, Barsille disappears and her corpse appears underwater in the Central Council Quarter sewers along with a murder note courtesy of the Cammona Tong.

Here is a link to my planning spreadsheet for the dialogue in this quest. It does not contain all the topics, greetings, and journal entries I ended up including and it does not match the finished version 1:1, but it should give you a rough idea of what you should be looking for.